polo engine in my ibiza, need some advise!

[gates16v]

i've got a mk3 ibiza 1.4mpi. engine is s**t as u all will know and came to an end during the flooding when i used it as a boat which it did not like! this wrote the engine off as u can imagine. now i work for a v.a.g specialist and got hold of an AFK 16v engine from a polo. this dropped straight into my ibiza without swapping the loom, only changing it slightly and also had to use a 1.6 16v leon throttle body. my only prob is it only revs to 5500rpm like the ibizas do, not 6800 which the engine is capable of. also when driving gently it over fuels and under fuels intermittently but is ok on full throttle. these are my only 2 issues. as i am running it on bosch management rather than the polo magnetti marelli i have my old ecu running it as the polo ecu will not work. 2 reasons being that it is diff make so the car wont work, other reason is that polos use throttle cable and my ibiza runs fly by wire! i've spoken to revo and they say it cannot be done without a lot of the loom being changed which i do not want to do. I was wondering if you guys had any ideas? like if i could get the 16v map put onto my ecu somehow?! or poss a chip or remap? im running out of ideas. oh and it overfuells on start up, you have to give it a rev when u start it up.

i know it its a lot to take in but i would really appreciate any ideas u may have. and also u may be wondering y i am on here asking about my ibiza, but i had a mk4 polo 16v not so long ago which i ditched! i will be getting another 1 asap but need to finish this 1st!

thanks alot 16v